Mineral oil cracking process



Feb. 27, 1945. J. H. JAMES MINERAL OIL CRAGKING lROCESS Filed July 7,1959 mmmIawOEP( OP INVENTOR ,alyst is used, it is preferably 'an oxideor com-- Patented Feb. 21, 1945 UNITED s'rArl-:s PATENT oFFIcE maaar.omcaacxmc mocass Joseph Hidy James, Pittsburgh, Pa., aaslgnor toClarence P. Byrnes, Pittsburgh, Pa., an trustee Application July 7,1939, Serial No. 283,209

z clam. (01.19642) y I above forty and occur- United States Patents1,836,325 and 1,836,326v

partial oxidation methods wherein the oxygen tied into the hydrocarbonvapor is withdrawn from metallic oxides (termed oxidants) in a hot zone.These metal oxides may be the same as the catalysts used in that form oimy process 'where free oxygen is employed such as contained in air; ormay be other metal oxides.

In either case, for cracking purposes, I preier' ably employ a mildoxidatibn, since any chemical tyingin of oxygen such as that sufficientto produce alcohols, greatly aids in cracking under low prescatalyst asilicate of a rare metal" such as molybdenum, vanadium, uranium,tungsten, etc.v Some of these may be prepared, for example, by

sures; and in both cases I preferably employ a plurality of crackingunits connected to one or more units for partial oxidation; and when andif clogging of the cracking catalyst occurs I intermittently shift the'exit stream from the partial oxidation step, from one cracking unit toanother cracking unit, and burn out the first one by admitting air or anair containing a. combustible. As soon as the rst unit is "burnt out"and the coatings of tar, carbon, etc., thus cleaned out, the stream fromthe oxidizing unit will be shifted back and cleaning out of the other,and alternate cracking unit eiIected. l

The air or combustible mixture for burning out is preferably fed intothe clogged cracking unit directly, or at" a point between the oxidizingand cracking unit and the stream of burnt gases is led from the crackingunit to the open air, suitable valve means being used to switch the exithaving an atomic weight ring on the descending sides of the4 Lothar-Meyer `atomic volume curve. The main examples thereof whose oxides arecatalytically active in oxidation are molybdenum, vanadium, tungsten,uranium, etc. Hereafter I shall term such metals rare metals".

In the cracking step, I prefer to employ a catalyst consistingpreferably of hydrosilicates, an acid or non-alkaline silicate or clay,an earth metal, or zeolites; since I have Iound these t0 be especiallyefficient in the cracking of the oi'gen derivatives of hydrocarbonformed in the lpatrial oxidation step. s The cracking temperature ispreferably in the range from about 300 C. to about 550" C.

I prefer especially to employ as a cracking adding a soluble salt oi therare metal such as a chloride or sulphate thereof to 'a solution ofsodium silicate. The rare metal silicate lwill be precipitated andshould be separated and washed free irom'the sodium salts formed. Othersrequire special methods oi preparation ofA their silicates. Such acracking catalyst has certain advantages, since the catalytic propertiesof the silicates are combined with similar properties of the rare metalswhich act as activators.

I am aware that silicates or hydrosilicates have been proposed ascracking catalysts for straight hydrocarbons, but so far as I am aware,no one has discovered their peculiar advantages' in cracking a mixtureof oxygen derivatives of aliphatic hydrocarbons in the range fromalcohols to'oxygenated acids, which are'produced in the partialoxidation of aliphatic hydrocarbons such as petroleum or its fractions.

In the drawing where I show dlagrammaticallya system of apparatus forcarrying out one form of my invention, 2 represents a vaporizer whereinthe raw. fraction or crude oil may be vaporized and the heavy residuetapped out, and 2a the reaction chamber for partial oxidation of themixture of vapor and air passing therein preferably in contact with acatalyst such as recited from 250 C. up to 600 C. preferably by employ-50 ing a cooling uid, and any of the well known types of catalytic cellsmay be used. If` a catpound or complex or a low atomic volume high in mypatents on partial oxidation. Leading therefrom are branch'pipes 3 and3a controlled by reversing valve B pivoted'at I and tilted to closeeither conduit. Eachv conduit 3, 3a leads` to a cracking chamber ,gla,one o! which (shown as la) is connected to the oxidation chamber 2a andclosed to-air supply pipe Il by valve Ila,

atomic weight polyvalent metal. especially those l5 while the other isclosed tothe oxidation chamber and is regenerated by air or air and fuelfed through pipe 1 whose valve 1als open. From the cracking chambersextend branched pipes 8, 8a and 9,' 9a, respectively, controlled byreversing valves i0, a, of which 8 and 8a lead to condensers,dephlegrnators, orl bubble towers, while 9 and 9a open to the outer air.

In this form air and oil vapor pass throughl the oxidizer, thetemperature of which is controlled within reactive limits, to tie freeoxygen from the air into the hydrocarbon chains, preferably to a milddegree. Thence the mixture containing oxygen derivatives passes into oneof the cracking units 4a where a cracking temperature is maintained andthence the cracked vapors pass to a condenser or bubble tower. Duringthis stage unit 4 is being regenerated and burnt out, the exit streampassing into the open air. After a few minutes, for example, 6-10minutes, the valves are reversed, the stream from the oxidizer is fed tothe other cracking unit 4 and air is fed to` unit 4a. to burn out thecoating collection on the cracking catalyst. When this burning out iscompleted, the valves are reversed.

In case the oxidant type of oxidation is carried out by withdrawingoxygen from an oxide' tion to remove a lower fraction boiling below therange of the fuel desired such as gasoline. The heavier portion may thenbe cracked, preferably in the vapor phase, with a cracking catalyst suchas herein described; or if desired in the-liquid phase, or in bothphases, with a catalyst.

One of the advantages of my process is that hydrogen is removed from thestock only in proportion to the oxygen chemically tied therein (exceptas to alcohol formation). Hence I can and do rerun the heavier portionremaining after gasoline removal following each run. In such caseexpensive high pressure cracking is not required for what is commonlycalled recycle stock as is the case where" excessive dehydrogenationtakes place.

Under my broader claims which include regenerating or burning out of thecracking cataas in my Patents 1,836,325 or 1,836,326, the partialoxidation unit will have means for withdrawing the oxidant and forreoxidizing and returning it to the unit for reuse. Otherwise theapparatus may be like that of the figure herein, or the oxidant may,after reduction to a lower oxide, be revivied in place or otherwise bypassing air over it while hot, to reoxidize it during the revivifying ofthe cracking catalyst. In this case, air would be fed over the oxidationcatalystwhile air or air and fuel passes through the cracking catalyst,during the revivifying phase of each. This would mean in effect twolines of apparatus, one on one part of the cycle and the other on theother or revivi'fying part, and each connected both to the condenser orbubble tower and also direct to the atmosphere.

In case the cracking catalyst is carried into and out of the crackingzone or unit, the steps of oxidation and cracking may be carried outmore continuously; and if the types of apparatus shown in my oxidantPatents Nos. 1,836,- 325 'and 1,836,326 of December 15,1931 are employedfor the cracking catalyst, no reversal of periods need be used. If insuch case the oxidant system of oxidation were also used, then both theoxidant and the cracking catalyst may be revivified as soon as used, byremoval, treatment with oxygen or oxygen and fuel, and then by return totheir chambers.

In all such systems heat may be supplied to the cracking unit during thecracking operation by external heat as desired; since the step here isendothermic while the oxidation step is exothermic. The layer ofcracking catalyst may be .and preferably is thicker or deeper than thatof theoxidation catalyst. The steps may be carried out under suction orunder pressure above the atmosphere. If pressure is used, it need beonly that sufficient to feed the mixture through the apparatus, sincethe oxidation step makes the cracking step easier and operative at lowerpressures than now used; though higher pressures may be used.

In another form of my invention, the condensate from partial oxidationsuch as my vapor phase partial oxidation (preferably carried out in mildform) may be condensed and the condensate preferably fractionated as bydistillalyst, I may use the same catalyst for cracking as I disclose inlmy patents for partial oxidation; such as molybdenum oxide, vanadiumoxide, etc., mounted on any suitable carrier therefor such as variousrefractory materials including clays, silicates, etc.; or I may use raremetal compounds or complexes such as disclosed in my several pat.- entsherein recited.

The cracking catalyst may be changed, various carriers therefor may beused; oxygen may be tied in in the absence of a catalyst; any of theoxidizing catalysts of my patents such as Reissue 18,522 of Septemberl5. 1936; 2,054,591 of September 15, 1936; 2,085,221 of June 29, 1937;or 1,739,620 of May 20, 1930 may be used and preferably those giving amild oxidation to vapors of heavy fractions.

In another variation of my process, the cracking of the oxidationproduct is carried out in the vapor phase thereof and in the presence ofhydrogen.

In such a process the oxidation product, preferably in the vapor phase,whether prepared by air oxidation or with an oxidant, is mixed withhydrogen and passed over catalysts, preferably consisting of my raremetal oxides such as vanadium oxide, molybdenum oxide, uranium oxide,tungsten oxide, etc.

By fthe term non alkaline in my claims I intend to include both acid andneutral agents.

The advantage of this phase of my invention lies in the fact that theuse of hydrogen prevents the formation of too great an amount of heavyhydrocarbon Ior heavy hydrocarbon derivatives low in hydrogen and whichcannot be recycled because of their low hydrogen content. This processwould also aid in lengthening the time of passage prior to such cloggingaction as would require revivifying of the cracking catalyst.

I claim:

l. In the treatment of petroleum, the steps consisting of vaporizing lapetroleum fraction f 2,910,541 a v 3zmmethodottrcatingmineraloilconmainly straight chain saturated al1-phatic hydrocarbons. consisting of vaporizing the same. mixing it with agas containing-free oxygen, partially'oxidizing the vapor-gas stream atelevated temperature in the presence of an oxidation catalyst containinga compound of a' low atomic' volumeQ high atomic weight4 polyvalentmetal. and then thermally decomposing a material percentage of .thc hotvapor-gas stream in another sone and in the presence of a crackingcatalyst containing naterial other than the said oxidation catalyst. A

JOSEPH HIDY JAMES.

